1. Field
The present disclosure relates to a driver circuit and a readout circuit configured to output to column lines the result of classifying photons according to their energy levels and counting the number of photons for each energy level.
2. Related Art
Radiation medical devices are being widely used and developed. An example of a radiation medical device is an X-ray imaging system, which exists in analog and digital forms. The change from analog to digital may be largely attributed to a rapid advancement of technology related to X-ray detectors, which are the core components of X-ray imaging systems.
Digital X-ray detection technologies are mainly classified into ones that perform an indirect detection method and ones that perform a direct detection method. In an indirect detection method, X-rays are first converted into visible light and then into electrical signals to produce an image. In a direct detection method, X-ray signals are directly converted into electrical signals to generate an image.
The direct detection method may be implemented in various modes including integration mode and photon counting mode. In the integration mode, electrical signals are accumulated for a time to produce an image signal. In the photon counting mode, the number of incoming X-ray photons is counted to produce an image signal. Recently, research has been very actively conducted on the photon counting mode because it allows generation of an image for each of a plurality of X-ray energy levels with one shot imaging and provides high quality images with low X-ray exposure.